Zebra mussels are small bivalve mollusks that are fingernail sized and native the Caspian Sea region of Asia.  These mussels are filter feeders and one mussel can filter one liter of water per day. In the water they feed primarily on phytoplankton, zooplankton, and algae.  When the water is filtered it creates several issues for a lake.  The clearer water increases plant growth and disrupts native mussel and fish species.  The broken shells are often sharp and often cut swimmers feet.  These mussels also attach to hard surfaces such as docks, boats, motors and other equipment.  Large amounts of money are often spent cleaning equipment to keep it functional.